(a) (i) Describe the distribution of the area with an average January temperature below 10 °C. [3]
Sample Answer;
The area with an average January temperature below 10°C is primarily located in western Pakistan. This includes the whole of the Northern Areas, which encompasses regions like Gilgit-Baltistan. Additionally, parts of western NWFP (now Khyber Pakhtunkhwa) and northern Balochistan experience temperatures below 10°C. The northern and western mountain ranges, such as the Hindu Kush and the Suleiman Range, are also part of this cooler zone. However, the temperature remains above 10°C in western Balochistan, which does not fall under this cooler category.
This general distribution highlights the cooler temperatures found in mountainous regions, with the highest altitudes in the northern and western parts of Pakistan.
(ii) Explain fully the distribution of the area with an average January temperature below 10 °C. [4]
The area with an average January temperature below 10°C is primarily found in the northern and western parts of Pakistan, and this distribution can be explained by several climatic factors.
Altitude: The most significant factor is the high altitude of the regions in question. The Northern Areas (including Gilgit-Baltistan), the northern parts of Khyber Pakhtunkhwa (KP), and northern Balochistan are located in mountainous areas, such as the Hindu Kush, the Suleiman Range, and the Karakoram Range. Higher altitudes generally lead to lower temperatures, especially in winter, due to the thinner atmosphere at higher elevations, which can't retain heat as effectively as lower altitudes.
Latitudinal Position: The regions with temperatures below 10°C are situated at higher latitudes, closer to the northern parts of the country. In January, these areas are farther from the equator, where solar energy is less direct, leading to cooler temperatures during the winter months.
Continental Position: Pakistan's position in the interior of the Asian continent also contributes to the cool temperatures in these areas. Continental areas, particularly those far from oceans or large bodies of water, experience more extreme temperature variations, and in the winter months, these regions cool down significantly due to the absence of moisture to moderate temperatures.
These three factors—altitude, latitudinal position, and continental position—combine to create the cold conditions in the northern and western mountainous regions of Pakistan in January, resulting in average temperatures below 10°C.
(iii) Why do some areas experience long periods with temperatures below 0 °C? [3]
Some areas in Pakistan experience long periods with temperatures below 0°C primarily due to the combination of altitude, climatic conditions, and the geographical features of the region.
1. Altitude: The most significant factor is the high altitude of these areas. Regions above 4000 meters, such as the northern mountainous areas (e.g., parts of Gilgit-Baltistan and the Karakoram Range), experience lower temperatures because temperatures decrease with altitude. In dry air, temperatures decrease by approximately 5°C for every 500 meters of elevation. Therefore, the higher the altitude, the colder the temperature, often resulting in sub-zero temperatures for extended periods.
2. Dry Air: Most of Pakistan experiences dry air, which enhances the cooling effect with altitude. Dry air cools faster than humid air, contributing to colder temperatures, particularly in the winter months.
3. Geographical Features: The narrow, deep valleys in mountainous areas also play a role in keeping temperatures below freezing. In winter, the sun's rays have a low angle and cannot penetrate deeply into these valleys, preventing the warming of the area. As a result, these valleys remain cold for longer periods.
These factors—altitude, dry air, and the geographical layout of narrow valleys—combine to cause long periods of temperatures below 0°C in the high-altitude regions of Pakistan.
(b) (i) Describe the distribution of the area with an average January temperature above 15 °C. [2]
The area with an average January temperature above 15°C is primarily located in southern Pakistan. This includes nearly the whole of Sindh and southern Balochistan. These regions experience warmer temperatures in January due to their lower latitude and proximity to the Arabian Sea, which helps moderate the temperature.
(ii) Explain fully the distribution of the area with an average January temperature above 15 °C. [3]
The distribution of the area with an average January temperature above 15°C in southern Pakistan can be explained by several factors:
1. Latitudinal Position: Southern Pakistan is located closer to the Tropic of Capricorn, where the sun is overhead on December 21st. This results in a higher angle of sunlight compared to the rest of Pakistan, leading to greater heating during the winter months. Though the sun is not directly overhead in January, its angle still provides more warmth than in northern regions.
2. Low Altitude: Much of Sindh is a lowland area, meaning temperatures are not significantly reduced by altitude. Since there are no major mountain ranges to block the sun's rays or cool the air, temperatures remain higher in these regions.
3. Maritime Influence: The proximity to the Arabian Sea means that the sea's heat retention helps moderate temperatures. Although the maritime influence is less pronounced in winter, when onshore winds occur, they bring some warmth from the sea, preventing temperatures from dropping too low.
These factors—latitudinal position, low altitude, and maritime influence—combine to keep the temperatures in southern Pakistan above 15°C in January.